Unlike light and electrons, there has not been a method available that can focus or bend gamma rays or their artificial equivalent high energy or hard X-rays controllably for use in microscopy. Light is known to be bendable by traveling through a transparent material of higher refractive index at an angle. Electrons have charges thus the flight path of electrons can be controlled by an electric field or a magnetic field. The shorter the wavelength of the radiation source used, the higher the achievable resolution can be. Gamma rays and X-rays are among the highest energy electromagnetic radiation with the shortest wavelength that can even penetrate dense materials such as lead.
Heisenberg theorized a model gamma-ray microscope that can achieve very high resolution by using high-energy gamma rays for illumination. He envisioned this gamma-ray microscope can be used to probe an electron's position to prove his uncertainty principle. However the lenses in his model can not be made so up until now no such gamma ray microscope exists.
Gamma rays are electromagnetic radiation of high energy. They are produced by sub-atomic particle interactions such as electron-positron annihilation. Gamma rays typically have frequencies above 1019 Hz or wavelength in the picometer range or smaller.
The short wavelength of gamma rays makes them desirable for use in high resolution probing of sample. According to existing microscopy's principle, the shorter the wavelength, the higher the resolution can be thus enabling higher magnification. This is why an electron microscope can have higher magnification and higher resolution than a light microscope.
The challenge is that since gamma rays can not be controlled in any way except for blocking by heavy shielding, it can only be used for non-magnifying methods of imaging such as Positron Emission Tomography aka PET scan. Similarly, high energy or hard X-rays are used to obtain an image of an object density, but no magnification can be done. As a result, instead of hard X-ray microscopy, X-ray diffraction patterns must be used to deduce the molecular structure of a molecule within a crystal to deduce the structure of molecules within. This is only possible for any molecules that can be crystallized because the repeatable patterns of the same molecule in the crystal are necessary for this method.